S-cyanobenzyl thio and dithiophosphonic acid esters



United States Patent Oflice 3,379,795 Patented Apr. 23, 1968 3,379,795 S-CYANOBENZYL THIO AND DITHIO- PHOSPHONIC ACID ESTERS Karl-Julius Schmidt, Wuppertal-Vohwindel, Germany, as-

signor to Farhenfabriken Bayer Aktiengesellschaft, Leverknsen, Germany, a corporation of Germany No Drawing. Continuation-impart of application Ser. No. 360,126, Apr. 15, 1964. This application Mar. 24, 1965, Ser. No. 442,508 Claims priority, application Germany, Dec. 3, 1964, F 42 461 15 Claims. Cl. 260-940) ABSTRACT OF THE DISCLOSURE Thioand dithiophosphonic acid esters of the formula wherein R is lower alkyl or aryl; R is lower alkyl and X is oxygen or sulfur.

wherein R stands for a member selected from the group consisting of lower alkyl and aryl radicals, preferably phenyl, R stands for lower alkyl and X stands for a chalkogen having an atomic weight less than 40 (i.e. oxygen or sulfur). R and R when both alkyl may be the same or different and preferably contain up to 4 carbon atoms.

In U.S. Patent 2,992,158, 0,0- and O,S-dialkyl-S-cyanobenzyl-phosphoric acid esters of the formula (II) RY Y N are described. According to the Patent R and R stand for lower alkyl radicals having 1 to 4 carbon atoms, Y and Y stand for oxygen or sulphur and R and R as well as Y and Y may be the same or different.

According to the above-mentioned U.S. patent, the phosphate cyanobenzyl compounds are useful as insecticides, acaricides and nematocides.

In accordance with the present invention it has now been discovered that alkyl or aryl-O-alkyl-S-(cyanobenzyl) esters of thio or dithiophosphonic acid according to Formula I are outstandingly superior to such known compounds and can be obtained by reacting thio or dithiophosphonic acids of the formula either in the form of the corresponding alkali metal, alkaline earth metal or ammonium salts, or in the presence of acid-binding agents, with cyanobenzyl halides. In Formula III, the symbols R and R have the same meanings as in Formula I.

The reaction according to the invention is preferably carried out with stoichiometric amounts of the starting materials concerned. However, the reaction proceeds with equally good results when one or the other component is used in excess. I

It has further proved to be expedient to carry out the reaction in the presence of an inert organic solvent. For this purpose, aromatic hydrocarbons such as benzene, toluene and xylene are particularly suitable. In addition to arbmatic hydrocarbons low boiling aliphatic ketones or nitriles such as acetone, methyl ethyl ketone, methyl isopropyl ketone or methyl isobutyl ketone as well as acetoor 'propionitrile and dimethyl formamide may be used.

.The process according to the invention can be carried out within a wide range of temperatures but it is advantageous to allow the reaction to proceed at a temperature between 20 and 150 C., preferably 40 to C., and to continue stirring the mixture, with further heating if desired, for from 2 to 5 hours after the starting components have been combined, in order to complete the reaction.

The thioor dithio-phosphonic acid esters according to the present invention are usually colorless to slightly colored oils which cannot be distilled without decomposition, even under greatly reduced pressure. The compounds can be freed from the last volatile components and purified by partial distillation, i.e. prolonged heating in a vacuum at slightly to moderately elevated temperatures.

The products of the present invention are distinguished by outstanding pesticidal, and in particular insecticidal and acaricidal properties. They are clearly superior in this respect against various pests as compared with compounds of analogous structure such as those from U.S. Patent 2,992,158.

The new compounds of the present invention show high activity and very effectively kill insects such as aphids, spider mites, caterpillars, beetles, flies, ticks, etc. They distinguish themselves particularly by good contact-insecticidal activity and also in many cases by systemic action.

Most surprisingly the compounds according to the invention are of remarkably lOW toxicity against warm lblooded animals. They may be used inthe same manner as'other known phosphoric insecticides, but are effective in low concentrations, e.g. in a concentration from about 0.00001% to about 1%. The compounds may be diluted or extended with suitable solid or liquid carriers or diluents. Examples of such solid carriers are talc, chalk, bentonite, clay and the like. As liquid carriers there may be mentioned water (if necessary with commercial emulsifiers), alcohols (especially lower alcohols such as methanol or ethanol), ketones (especially lower ketones such as acetone or methyl ethyl ketone) liquid hydrocarbons and the like. The new compounds may furthermore be used in mixtures with each other or with known insecticides, fertilizers, etc.

As examples of particularly outstanding inventive compounds containing the 4-cyanobenzyl ester group, those of the following formulae "can be mentioned:

These compounds were tested against spider mites, ticks (compound IV) and aphids (compound V).

Aqueous dilutions of the compounds were prepared by mixing the active ingredients with the equal amounts of dime'thyl forniamide as an auxiliary solvent, adding thereto 20% by weight based on active ingredient of a commercial emulsifier consisting of benzyl hydroxy polyglycol ether containing about 10 to 15 glycol ethers, and diluting this premixture with water to the desired concentration indicated in the following paragraphs.

The tests were carried out as follows:

(a) Against spider mites: Bean plants (Phaseolus vulgar-is) of about 15 inches height are sprayed drip wet with solutions as prepared above and in a concentration as shown below. The beam plants have ben infested heavily with the two-spotted spider (species T etranychus telarius) Evaluation has been carried out after 24 hours, 48 hours, and '8 days. The following results were obtained:

Aqueous concentration Killing rate Compound (in percent active (in percent) ingredient/water) Aqueous concentration Killing rate Compound (in percent active (in percent) ingredient/water) (c) Against aphids (contact-insecticidal action) of the type Doralis fabae: Heavily infested bean plants (Vicia faba) have been sprayed drip wet with solutions as prepared above. The etfect has been determined by evaluation after 24 hours by counting the dead pests either on the surface of the soil or still remaining on the plants. The following results were obtained:

Compound V:

Aqueous concentration (in active ingredient/ water) 0.0 1 Killing rate (in percent) 100 As a comparison of insecticidal activity of the compounds of the invention with compounds of analogous structure known from US. Patent 2,992,158, the following compounds were tested in a like manner and the results shown below.

Compounds tested (:1) against spider mites Aqueous concentration Killing rate Compound (in percent active (in percent) ingredient) v1 o. 001 .100 o. 0008 (VII) 07 01 100 V 0. 001 0 Aqueous concentration (in percent active Killing rato Compound (in percent) ingredient) 5 (VI) 0. 05 0. 0025 0 (VII) 1- 0. 025 0. O1 0 10 those of the following formulae can be mentioned.

As a comparison of insecticidal activity with compounds of analogous structure known from US. Patent 2,992,158 the following compounds were tested in a like manner and the results shown below.

(CH)2PSCH2 o2H o)lP-s-orir (a) against spider mites Aqueous concentration Killing rate Compound (in percent active (in percent) ingredient) (b) against ticks Aqueous concentration Killing rate Compound (in percent active (in percent) ingredient) (VIII) 0. 05 100 0. 002 [55 r (IX) o. 0025 100 00 0. 001 (X) 0. ()5 30 0.0025 0 0. 001 0 (XI) 0.1 75 0. 01 0 (c) against caterpillars Aqueous concentration Killing rate Compound (in percent active (in percent) ingredient) The following examples are given for the purpose of illustration only and do not constitute express or implied limitations.

Example 1 0 11 T,

taken up in 500 ml. of toluene, the soluble components are removed by washing with water, the organic layer is dried over sodium sulfate with the addition of animal charcoal, the solvent is removed from the filtrate under reduced pressure finally at 0.01 mm. Hg and C. The yield amounts to 220 g. (96% of the theoretical) of ethylthionothiol phosphonic acid O-ethyl-S-(4-cyanobenzyl) ester which is obtained in the form of an oil.

Analysis.Calculated for C H ONS P (molecular weight 285.37): N, 4.91%; P, 10.85%; S, 22.47%. Found: N, 5.09%; P, 10.68%; S, 22.11%.

Spider mites are completely destroyed by 0.001% solutions, ticks by 0.005% solutions of the compound.

In an analogous manner to that described in Example 1, 90 g. (0.6 mol) of 4-cyanobenzyl chloride are reacted with 162 g. (0.6 mol) of phenyl-O-ethyl-thionothiolphosphonic acid potassium salt, 172 g. (86% of the theoretical) of phenyl-thionothiol-phosphonic acid-O- ethyl-S-(4-cyanobenzyl)ester of melting point 172 C. being thus obtained.

Analysis.Calculated for C H ONS P (molecular weight 333.42): N, 4.20%; P, 9.30%; S, 19.24%. Found: N, 4.52%; P, 8.99%; S, 18.98%.

Spider mites are completely destroyed by 0.1% solutions of the ester.

Example 2 Example 3 Under reaction conditions analogous to those described in Example 1, 36.5 g. (0.24 mol) of 4-cyanobenzyl chloride are reacted with 55.5 g. (0.24 mol) of isopropyl- O-ethylthionothiol-phosphonic acid potassium salt. grams (91% of the theoretical) of isopropyl-thionothiolphosphonic acid-O-ethyl-S-(4-cyan0benzyl) ester are obtained.

Analysis.Calculated for C H ONS P (molecular weight 299.4): N, 4.68%; P, 10.35%; S, 21.42. Found: N, 4.78%; P, 10.46%; S, 21.22%.

Spider mites are killed 100% by 0.01% solutions of the compound.

Example 4 CH: S

CzHsO Analogously to Example 1, there are obtained from 36.5 i

g. (0.24 mol) of 4-cyanobenzy1 chloride and 48.5 g. (0.24 mol) of methyl-Oethyl-thionothiol-phosphonic acid potassium salt, 58 g. (89% of the theoretical) of methyl thionothiol phosphonic acid O ethyl S- (4-cyanobenzyl) ester.

Analysis.--Calculated for C H ONS P (molecular weight 271.3): N, 5.16%. Found: N, 5.60%.

Spider mites are completely destroyed by 0.001% solutions, aphids by 0.01% solutions of the product.

Example 5 Analogously to Example 1, there are obtained from 36.5 g. (0.24 mol) of 4-cyanobenzyl chloride and 59 g. of isobutyl-O-ethyl-thionothiol-phosphonic acid potassium salt, g. (93.5% of the theoretical) of isobutyl-thiono thiol-phosphonic acid-O-ethyl-S-(4-cyanobenzyl) ester.

6 Analysis.--Calculated for C H ONS P (molecular weight 313.4): N, 4.47%; P, 9.89%; S, 20.46%. Found: N, 4.50%; P, 10.04%; S, 20.57%.

Spider mites are killed 100% by 0.01% solutions of the product.

Example 6 S CH3 I C2 s CN 38 grams (0.25 mol) of 3-cyanobenzyl chloride and 49 g. of methyl-O-ethyl-thionothiol-phosphonic acid potassium salt are stirred in 200 cc. of acetonitrile at 70 C. for 3 hours. The reaction mixture is subsequently mixed with 400 ml. of benzene, cooled, washed several times with water, dried over sodium sulphate and evaporated under strongly reduced pressure, finally at a bath temperature of 70 C. and at 0.01 mm. Hg. The yield amounts to 62 g. (91% of the theoretical) of methylthionothiol phosphonic acid-O-ethyl-S-(3-cyanobenzyl) ester.

Analysis.Calculated for a molecular weight of 271.3: N, 5.16%; P, 11.41%. Found: N, 5.54%; P, 10.74%.

Example 7 38 grams (0.25 mol) of 2-cyanobenzyl chloride and 48.5 g. of methyl-O-ethyl-thionothiol-phosphonic acid potassium salt are stirred in 200 cc. of acetonitrile at 70 C. for 3 hours. After cooling, the reaction mixture is poured into 300 ml. of benzene, the benzene solution is washed several times with water, dried over sodium sulphate, the benzene is evaporated under reduced pressure, finally at 70 C. and 0.01 mm. Hg, and 61 g. of the theoretical) of methyl-thionothiol-phosphonic acid-O-ethyl-S-(2-cyanobenzyl) ester are obtained.

Analysis.Calculated for a molecular weight of 271.3: N, 5.14%; P, 11.42%. Found: N, 5.67%; P 10.13%.

Example 8 Example 9 O C211 ON In a manner analogous to that described in Example 6, 52 g. (70% of the theoretical) of isopropyl-thionothiolphosphonic acid-O-ethyl-S-(2-cyanobenzyl) ester are obtained from 38 g. of 2-cyanobenzyl chloride and 56 g. of isopropyl-Oethyl-thionothiol-phosphonic acid potassium salt.

Analysis.-Calculated for a molecular weight of 299.4: N, 4.68%; P, 10.34%; S, 21.42%. Found. N, 4.98%; P, 10.32%; S, 20.76%.

7 Example 10 S C4H9 By reacting 38 g. of Z-cyanobenzyl chloride with 59 g. of isobutyl-O-ethyl-thionothiol-phosphonic acid potassium salt in the manner described in Example 6, 76 g. (99% of the theoretical) of isobutyl-thionothiol-phosphonic acid-O-ethyl-S-(Z-cyanobenzyl) ester are obtained.

AnaIysz's.--Calculated for a molecular weight of 313.4: N, 4.45% P, 9.89%; S, 20.46%. Found: N, 4.59%; P, 9.48%; S, 20.55%.

Example 11 The reaction of 38 g. of 2-cyanobenzyl chloride with 52 g. of phenyl-O-methyl-thionothiol-phosphonic acid potassium salt in a manner analogous to that of Example 6 yields 69 g. (86.5% of the theoretical) of phenylthionothiolphosphonic acid-O-methyl-S (2-cyanobenzyl) ester.

Analysis.Calculated for a molecular weight of 319.4: N, 4.39%; P, 9.70%. Found: N, 4.80%; P, 8.88%.

I claim:

1. A compound of the formula wherein R stands for a member selected from the group consisting of lower alkyl having up to 4 carbon atoms and phenyl, R stands for lower alkyl having up to 4 carbon atoms and X stands for a chalkogen having an atomic weight less than 40.

2. A compound of the formula wherein R and R stand for lower alkyl having up to 4 carbon atoms.

3. A compound of the formula wherein R and R stand for lower alkyl having up to 4 carbon atoms.

4. A compound of the formula wherein R and R stand for lower alkyl having up to 4 carbon atoms.

5. The compound of the formula CzlInO 6. The compound of the formula (32 50 7. The compound of the formula tour, s

PSCH2 CN C2HsO 8. The compound of the formula CH3 s \l! /Ps-oI-h CN 021150 9. The compound of the formula 1C4H9 S \il /PSCHz CN 6 10. The compound of the formula CH3 S 11. The compound of the formula 12. The compound of the formula 01115 i 13. The compound of the formula iOaHT S Q P-S-CHz- I 14. The compound of the formula 15. The compound of the formula 1-SCI-Ia- CHa0 l References Cited UNITED STATES PATENTS 7/ 1961 Berkelhammer et al.

260-940 X 1/ 1965 Schrader 260940 CHARLES B. PARKER, Primary Examiner.

A. H. SUTTO, Assistant Examiner. 

